Rockwell Automation 1762-Lxxxx MicroLogix 1200 Programmable Controllers - Manual (Page 132)

Publication 1762-UM001G-EN-P - March 2011
E-2 Connect to Networks via RS-232 Interface
Example DF1 Full-duplex Connections
For information about required network connecting equipment, see Chapter 4,
Communication Connections.
We recommend using an AIC+, catalog number 1761-NET-AIC, as your
optical isolator.
DF1 Half-duplex Protocol DF1 Half-duplex protocol is a multi-drop single master/multiple slave
network. DF1 Half-duplex protocol supports data transparency (American
National Standards Institute ANSI - X3.28-1976 specification subcategory
D1). In contrast to DF1 Full-duplex, communication takes place in one
direction at a time. You can use the RS-232 port on the MicroLogix 1200 as
both a Half-duplex programming port and a Half-duplex peer-to-peer
messaging port.
MicroLogix 1200 can act as the master or as a slave on a Half-duplex network.
When the MicroLogix 1200 is a slave device, a master device is required to
‘run’ the network. Several other Allen-Bradley products support DF1
Half-duplex master protocol. They include the SLC 5/03 and higher
processors, enhanced PLC-5 processors and Rockwell Software RSLinx
(version 2.x and higher).
DF1 Half-duplex supports up to 255 devices (address 0 to 254) with address
255 reserved for master broadcasts. As a DF1 Half-duplex slave device, the
MicroLogix 1200 supports broadcast reception. As a DF1 Half-duplex master,
the MicroLogix 1200 supports both the reception and initiation of broadcast
write commands (via the MSG instruction). The MicroLogix 1200 also
supports Half-duplex modems using RTS/CTS hardware handshaking.
TERM A B COM SHLD CHS GND TX
TX PWR
TX
DC SOURCE CABLE EXTERNAL
TERM A B COM SHLD CHS GND
TX
TX PWR
TX
DC SOURCE CABLE
EXTERNAL
Personal Computer
Modem cable
Modem
Modem
Optical Isolator
1761-CBL-PM02
MicroLogix 1200
Personal Computer
MicroLogix 1200
Optical
Isolator
1761-CBL-PM02
1761-CBL-AM00 or 1761-CBL-HM02